Blade structure of axial fan

ABSTRACT

A blade structure of an axial fan is disclosed. The blade structure includes a hub and a plural of fan blades. The fan blades are disposed equidistantly on a periphery of the hub along a rotating direction of the hub. Each fan blade includes a first blade and a second blade. The first blade has a first leading edge and a first trailing edge, and the second blade having a second leading edge and a second trailing edge. A line connecting the first leading edge and the first trailing edge of each fan blade is a first chord line. The second leading edge is located at a line extended along the first chord line, and the separation between the first blade and the second blade is smaller than a distance of adjacent fan blades on the periphery of the hub.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an axial fan and, in particular to a blade structure of an axial fan with high working efficiency.

2. Description of Related Art

Axial machine plays an important role in human industry. Fans, blowers, bumps, and propellers, for example, are used of axial blades for driving or transmitting fluid. Therefore, it is very important to improve the performance of axial machines for working efficiency and energy savings, and it's also a target for the industry continues to pursue.

Take fans for an instance, an axial fan usually includes a motor, a hub and a plural of blades. The hub is rotated by the driving of the motor, and fluid is flown by the push of the blades. To improve the characteristic of static pressure and air flow rate (P-Q curve) of the axial fan for pushing the fluid, a best performance is achieved through adjusting the size and angle of the blades. However, a limited success is achieved up to now.

Thus, how to improve the working efficiency of blades without increasing the product cost for getting a greater air volume and a higher air pressure are important issues in the industry.

In view of the above drawbacks, the Inventor proposes the present invention based on his expert knowledge and elaborate researches in order to solve the problems of prior art.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a blade structure of an axial fan to improve the characteristic of the static pressure and air flow rate (P-Q curve) of the axial fan for pushing the fluid. Thus a higher air pressure and a greater air volume are achieved for improving the working efficiency.

In order to achieve the object mentioned above, the present invention provides a blade structure of an axial fan including a hub and a plural of fan blades. The fan blades are disposed equidistantly on a periphery of the hub along a rotating direction of the hub. Each fan blade includes a first blade and a second blade. The first blade has a first leading edge and a first trailing edge, and the second blade having a second leading edge and a second trailing edge. A line connecting the first leading edge and the first trailing edge of each fan blade is a first chord line. The second leading edge is located at a line extended along the first chord line, and a separation between the first blade and the second blade is smaller than a distance of adjacent fan blades on the periphery of the hub.

Comparing to the prior art, each fan blade of the blade structure of an axial fan of the present invention includes of a plural of blades (at least one first blade and a second blade). Moreover, because there is a separation between the blades, and the second leading edge is located at a line extended along the line between the first leading edge and the first trailing edge (the first chord line). Therefore, the flow above the surface of the first blade could be maintained and the momentum of the boundary layer can be reinforced at the downstream. Therefore, a separation phenomenon will be delayed or minimized, and the thickness of the boundary layer of fluid will be reduced. Thus, the P-Q curve and consumption efficiency of axial machines will be enhanced. Moreover, the present invention also has characteristics of low cost and easy implement. BRIEF DESCRIPTION OF DRAWING

The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself, however, may be best understood by reference to the following detailed description of the invention, which describes a number of exemplary embodiments of the invention, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective schematic view of a blade structure of an axial fan of the present invention;

FIG. 2 is a top view of a blade structure of an axial fan of the present invention;

FIG. 3 is a side view of a blade structure of an axial fan of the present invention;

FIG. 4 is a cross sectional view of a blade structure of an axial fan of the present invention;

FIG. 5 is a flowing schematic view of a blade structure of an axial fan of the present invention;

FIG. 6 is a P-Q curve of a blade structure of an axial fan of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In cooperation with attached drawings, the technical contents and detailed description of the invention are described thereinafter according to a number of preferable embodiments, being not used to limit its executing scope. Any equivalent variation and modification made according to appended claims is all covered by the claims claimed by the present invention.

Please refer to FIG. 1 and FIG. 2, they depict a perspective schematic view and a top view of a blade structure of an axial fan of the present invention. The present invention provides a blade structure of an axial fan including a hub 10 and a plural of fan blades 20. The fan blades 20 are combined on the hub 10. The hub 10 is driven to rotate with the fan blades 20 to push surrounding fluid flowing.

The hub 19 is a cylinder including a top plate 11 and a side plate 12 extended from a periphery of the top plate 11, and the side plate 12 encloses one side of the top plate 11 for forming a peripheral surface 101 of the hub 10. In practice, the top plate 11 and the side plate 12 could be, but not limited to, integrally formed of the hub 10. The fan blades 20 are disposed equidistantly on a periphery of the hub 10 along a rotating direction of the hub 10. Each fan blade 20 includes a first blade 21 and a second blade 22 arranged at intervals. The first blade 21 has a first leading edge 211 and a first trailing edge 212, and the second blade 22 has a second leading edge 221 and a second trailing edge 222.

In an embodiment of the present invention, each fan blade 20 includes two blades (a first blade 21 and a second blade 22), however, the quantity of blades of the fan blade 20 is not limited. For instance, each fan blade 20 can include three blades.

With further referring to FIG. 3 and FIG. 4, they depict a side view and a cross sectional view of a blade structure of an axial fan of the present invention. In each fan blade 20, a line connecting the first leading edge 211 and the first trailing edge 212 is a first chord line 213. The second leading edge 221 is located at a line extended along the first chord line 213. Furthermore, the separation 210 between the first blade 21 and the second blade 22 is shorter than a g distance 200 of adjacent fan blades 20 on the periphery 101 of the hub 10.

In the present embodiment, the first blade 21 and the second blade 22 of the present invention could be provided in any proper shape of blades. A surface area of the first blade 21 and a surface area of the second blade 22 could be equal or unequal. Besides, a shape of the first blade 21 and a shape of the second blade 22 could the same or not the same. Moreover, a cross sectional area of the first blade 21 and a cross sectional area the second blade 22 at the corresponding position could be the same or not the same.

Preferably, the separation 210 between the first blade 21 and the second blade 22 is smaller than the one third of the length of the first chord line 213, and the second trailing edge 222 is located at a line 2130 extended along the first chord line 213, but not limited to.

Please also refer to FIG. 5, it depicts a flowing schematic view of a blade structure of an axial fan of the present invention. When the fan blades 20 rotate, the fluid will be conducted into the fan blade 20. Firstly, the fluid flows through the first blade 21, and then flows to the second blade 22 along the surface of the first blade 21. As the separation 210 is existed between the first blade 21 and the second blade 22, and the second leading edge 221 of the second blade 22 is located at the line 2130 extended along the first chord line 213. Thus the flow formed above the surface of the first blade 21 will be maintained in the separation 210 and being reconstructed. Therefore, a separation phenomenon will be delayed or minimized, and the thickness of the boundary layer of fluid will be reduced.

Flowing through the first blade 21, a vortex could be eliminated by the disposing of the first blade 21 and the second blade 22. In the present invention, the separation phenomenon occurred between the fluid and the fan blades 20 could be avoided or minimized when the fluid flow through the fan blades 20 by the deposition of the corresponding location of the first blade 21 and the second blade 22. Therefore, the flow above the surface of the first blade 21 could be maintained and the momentum of the boundary layer can be reinforced at the downstream, and the resistance between the fluid and the fan blades 20 will be reduced to get a maximum efficiency.

With referring to FIG. 6, it depicts a P-Q curve of a blade structure of an axial fan of the present invention. As shown in FIG. 6, a P-Q curve 30 of the fan blade structure of an axial fan of the present invention is higher than a P-Q curve 40 of a traditional axial fan. Thus, the blade structure of an axial fan of the present invention greatly enhances the mechanical performance of the axial machines in a condition without increasing energy consumption.

It is worth of note that the fluid on the present invention is included but not limited to fluid such as air, water or oil.

Although the present invention has been described with reference to the preferred embodiment thereof, it will be understood that the invention is not limited to the details thereof. Various substitutions and improvements have been suggested in the foregoing description, and others will occur to those of ordinary skill in the art. Therefore, all such substitutions and improvements are intended to be embraced within the scope of the invention as defined in the appended claims. 

What is claimed is:
 1. A blade structure of an axial fan, comprising: a hub; and a plural of fan blades disposed equidistantly on a periphery of the hub along a rotating direction of the hub, and each fan blade including a first blade and a second blade arranged at intervals, the first blade having a first leading edge and a first trailing edge, the second blade having a second leading edge and a second trailing edge; wherein, a line connecting the first leading edge and the first trailing edge of each fan blade is a first chord line, the second leading edge is located at a line extended along the first chord line, and a separation between the first blade and the second blade is smaller than a distance of adjacent fan blades on the periphery of the hub.
 2. The structure according to claim 1, wherein the separation between the first blade and the second blade is smaller than the one third of the length of the first chord line.
 3. The structure according to claim 1, wherein the second trailing edge is located at a line extended along the first chord line.
 4. The structure according to claim 1, wherein a surface area of the first blade and a surface area of the second blade are equal.
 5. The structure according to claim 1, wherein a surface area of the first blade and a surface area of the second blade are unequal.
 6. The structure according to claim 1, wherein a shape of the first blade and a shape of the second blade are the same.
 7. The structure according to claim 1, wherein a shape of the first blade and a shape of the second blade are not the same.
 8. The structure according to claim 1, wherein a cross sectional area of the first blade and a cross sectional area the second blade at the corresponding position are the same.
 9. The structure according to claim 1, wherein a cross sectional area of the first blade and a cross sectional area the second blade at the corresponding position are not the same. 